Hoist control and drive



Sept. 17, 1946. H. F. VICKERS I HOIST CONTROD AND DRIVE Filed Aug. 5.1940 zsheets-sheet 1 v i v v N 7" I l 2 S P 1 1946- H. F. VICKERS 7,694.

HOIST GONTROL AND DRIVE Filed Aug. 5, 1940 2 Sheets-Sheet 2 ATTORNEYS.

Patented Sept. 17, 1946 HQIST CONTROL AND DRIVE Harry F. Vickers, Detroit, Mich, assignor to Vickers Incorporated, Detroit, Mich., a corporation of Michigan Application August a, 1940, Serial No. 350,519

19 Claims.

This invention relates to a hoist control and has particularly to do with a hoist mechanism driven by a hydraulic motor and a hydraulic pump.

It is an object of the present invention to provide a control mechanism which is normally servo-operated but which may be operated without servo power in case of failure of certain elements of the system.

A further object is to provide a servo controlled unit in which the speed signal is limited by the position of, the hoist. Another object of the invention has to do with a provision for safely stopping the elevator or hoist in case of power failure.

Another object of the invention has to do with a means for maintaining the hydraulic pressure source at slight output when the motor is inoperative and means for bypassing said output.

Other objects and features of the invention having to do with details of construction and the hydraulic circuit, including the operation of the same, will be brought out in the following description and claims.

In the drawings:

Fig. 1 is a circuit diagram substantially diagrammatic showing the various elements of the system.

Fig. 2 is an enlarged sectional view of a portion of 1 showing the main elements of the hy- 1 draul c control.

In Fig. 1 ,a hoist car ii) is supported by an operating cable controlled by a drum l2. The drum I2 is driven by a reversible, variable speed, motor I3 through suitable gears l4 and I5. A brake unit It is connected to gear I5 by a gear Connected also to the drum l2 through suitable gearing IB is a cam wheel I9. Housed within a tank 28 are a reversible variable displacement hydraulic pump 2| and a control valve block 22 (see Fig. 2). The pump 2| is driven by a shaft 23 from an electric motor 24 which also drives a pilot or booster pump 25. Tank 25 serves as a main source of liquid for the hydraulic control circuit and a supplemental tank 23 has functions which will he described later.

An electrical circuit is provided to permit operation of the elevator 0r hoist only when certain conditions are met. A solenoid 33 operates a venting valve 3| in the valve block 22. The venting valve which will be described later is of such a nature that the elevator cannot be operated unless it is shifted against a spring 3| (1 by the energized solenoid 3D. The first condition for the movement of the hoist is that the electric motor 24 be operating. Consequently, the energy of the electric circuit is taken from the motor. One line 32 leads from the motor to the solenoid 33'. Another line 33 leads to a switch 34 which is connected to a door 35, shown diagrammatically at the upper station A. From switch 34, which is closed when door 35 is closed, the circuit to solenoid 3|] follows a line 36 to a starting switch 31. A line 38 connects through a switch 39 to line 40 leading to solenoid 33. Switch 39 is operatively connected to a door-4| at the lower station B. l

At each station, A and B, is provided a limit switch 42 and 43, respectively. When car In is at its lower limit, as shown in the drawings, switch 43 is open. When the car reache it upper position, switch 42 is open. During the travel of the car between the stations the starting switch 3'! may be released since both switches 42 and 43 will be closed and the circuit between. lines 36 and 38 is completed by a line 44, switch 42, a line 45 and switch 43. Line 33 is shunted to line 35 through a line 46 and a switch 41 which is closed when the car I0 is at its upper station by a cam slide Illa on the car. This shunting of line 46 permits operation of the car In between two loading levels at the upper station with door 35 open. The switch 42 controls the upper level and a switch 48 in line 45 controls the lower level, the switch 48 having an arm 49 which operates the switch when pressed downwardly but not when pressed upwardly. A small projection 50 on the car is arranged to contact switch 49. Switches 42 and 43 are operated by a projection 5| on the car.

Pump 2| is connected to motor |3 by conduits and 56. The pump 2| has a movable member 5'! which, when shifted to the right as viewed in Fig. 2, will cause pressure to be directed from conduit 56 to conduit 55 and thence to the motor to effect a hoisting movement. When the movable member 51 is displaced to the left, there will be a lowering action. Since the weight of the elevator will tend to drive the motor IS, the line 55 will be under pressure and fluid will be flowing through pump 2| to line 56. There is a closed circuit between pump 2| and motor I3 and this circuit is super-charged through a check valve 53 open to a line 59 and booster pump 25. In the event of failure of the booster pump, replenishing of line 56 may take place through a conduit 6B and a gravity valve 6| supplied by a tank 26 which is located at a level sunicient to supply a head of oil.

The basic control of the hoist is through the movable member 51 on pump 2|; this member is pivo ed as at 62 and normally is shifted by a servo mechan sm which controls the movement of a motor piston 63. The piston 63 is located in a cylinder 64 and has a rod 65 connected to a link 66 and by the link to the movable head 51. The rod 65 has a restriction 6'! which servesas a valve, as will be described later. The piston 63 is to be shifted by pressure from the booster pump 25, said pressure being conducted to the housing 22 by a line 68. When venting valve 3| is in the position shown in Fig. 2, the solenoid 30 being deenergized, line 68- is vented to a line 69 leading to tank 26. Above the venting valve 3| in housing 22 is a servo-valve l9 and above the servo-valve is a shuttle valve .As shown in the drawings, the shuttle valve normally bypasses conduits 12 and 13 leading to the. respec tive ends of cylinder 64. 'When venting valve 3| is shifted to the left, as viewed in the drawings, by the energization of the solenoid 30, line 68 will be cut off from line 69 and pressure from booster pump 25 will be directed to a line 14. Pressure in line 14 will shift shuttle valve H to the right, closing conduit 12 from conduit 13, but opening the end of conduit 14 to conduit 13, thus admitting pressure to the differential end of pressure piston 63. Because of the location of tank 26, and the connection pipe 69, there is a head of oil maintained on lines l2, 13 when the valves are in the position shown and the hoist is notbeing operated. Consequently, when valve 10 is in the position shown, a shifting of valve H to admitpressure to the differential end of piston 63, will not cause shifting of the piston since the liquid to the left of piston63 cannot escape. The servo-valve 10 is controlled by a rod 15 leading from a shaft 16 controlled by a lever 11.

Assuming that the elevator is to be hoisted,

is raised. Since piston 63 is temporarily stationary. a movement of a bell crank 18 will shift valve 10 to the left, through a lever 18a and link A restriction I9 in conduit 12 limits the velocity of the piston 63 and, therefore, limits acceleration or'deceleration of the hoist. If the hoist is to be lowered, lever 11 is lowered, thus resulting in a downwardmovement of rod 15. This will shift the valve 10 to th right by reason of the movement of bell crank 18 and lever 18a. Pressure will then be admitted from line 68 to line 12 and the head end of piston 63, thereby shifting it to the right. In each case, of course, a movement of the piston 63 and its rod 65 will compensate for movement of the valve land there will thus be a follow-up or servo movement.

At each side of pump 2| are cylinders 80 and 8| in which are located pistons 82 and 83; these pistons have rods extending to a projection 84 on the movable head 51 and each is urged toward this projection by springs 85 and 86. A conduit 81 connects one end of the cylinder of piston 83 to conduit 56 while the other end is connected by a conduit 88 to conduit 55 and also to housing 22 at the restriction in the rod 65. The cylinder '80 for piston 82 is connected by a conduit 89 to 4O lever "i lifted and by this movement rod 15 shown, the conduit 88 is connected through a conduit 9| to the venting valve and through the venting valve to a conduit 92 leading to conduit 56 of the main pump. Consequently, there is no pressure in either cylinders 89 or 8| and the springs 85 and 86 are free to act. These springs are so adjusted that they will hold th movable head 51 slightly off center toward the hoist side. The output of the pump 2| is, therefore, through conduit 55 but this output is bypassed through conduit 88, the valve restriction 6'|, conduit 9|, venting valve 3| and conduit 92.

The effect of shifting of the venting valve 3| to the right is to connect cylinder 89 to the pressure in conduit 55 through conduit 69, around piston rod 65, through a conduit 93, to conduit 89. Branch 88a also connects cylinder 9| to the pressure in conduit 55. Line 81 is necessary to insure shifting of piston 83 by equal displacement from either line of the closed operative circuit.

In addition to the brake |6, another safety device is provided in a safety latch 95 which is controlled by a spring pressed piston 96. A piston 91 Within a cylinder 98 at brake I6 and also the piston 96 are controlled by pressure from the booster pump 25 by reason of lines 99 and I09 leading, respectively, from conduit 68. When venting valve 3| is open, the brake |6 will be enaged and the latch 95 will be engaged providing the car is in its uppermost position. Upon the shifting of valve 3| .and the building up of pressure in line 68, piston 96 will beretracted and, similarly, piston 9l will be retracted, thus releasing latch 95 and brake l6.

In case of failure of the booster pump or any of the pressure lines connected therewith, a mechanism is provided to permit operation of the hoist without servo-power. A shaft |0|, operable by a lever I92, controls, by suitable arm connections, the piston 96 and the piston 91. For example, if lever I92 is shifted from its P position to its W position, latch 95 will be retracted and brake l6 will be released. A further connection is provided, through a rod I03, So that upon such shifting of lever I92, the valve 16 will be locked in its neutral position as viewed in Fig. 2. The locking of valve 19 is accomplished by a cam I94 which is moved by the shifting of rod I33. Since, due to booster pump failure, pressure is absent from lines 68 and 14, the valve H is spring impelled to bypass the stroke cylinder lines 12 and 13 to the replenishing tank line 69. Stroke piston 63 is, therefore, allowed free movement and the differential bypass is compensated for by the connection with tank 26. ,The head of oil from the tank -26 prevents aeration. Manual application at lever 11 now controls the pump head 51 without lost motion through rod 15, bell crank 18 and lever 18a, which is now pivoted at link 18b. Replenishing of the operating circuit is obtained through gravity check 6| from tank 26. The re- -mainder of the circuit functions the same as previously described.

The tank 26 is fed by surplus oil from the booster pump through line I05 and check valve I06. The overflow from this tank is carried through line I61 to tank 20. The booster pump normally draws oil through oil filters I08 in tank 26 and a conduit I89. These two filters are :mounted parallel in the circuit and are provided with plunger operated check valves. By this means one of them may be removed at a time while the other is operating. Air line H9 transfers air between tanks 29 and '26 due to fluid displacement. When the booster pump 25 is vented through valve 3|, a restriction HI maintains a back pressure in line 59 thus keeping the operating circuit supercharged even while idling.

Cam l9 limits the amount the lever 11 may be shifted. A the lever shaft 16 is also connected, a previous'y described, to a servo-valve it which controls pump offset, it can be seen that cam l9 controls the maximum rate of speed as well as deceleration and acceleration of the hoist. This is accomplished by reason of a lever or follower H2 which rides on the circumference of the cam which is properly shaped to control the movement of the shaft in conjunction with the movement of the motor l3 and the hoist car It]. A cam H3 on car IE is arranged to contact a lever its on its movement from the top level at th upper station to the lower level to cause deceleration as the hoist is moved between levels at the upper station. This is accomplished through a rod H5 which connects to the shaft 13.

An object of the present invention has been to provide a, hoist circuit which will perform safely even in the event of power failure or rupture of any of th lines. In case of power failure, that is, failure of the electric power driving motor 25, means has been provided to stop the hoist in the smoothest and safest possible manner. While in the lowering stroke, it will be noted that line 38 remains open to line 9| through the restriction 6? in rod 65 of stroke piston 63. In the event of power failure while lowering, the solenoid 3i would be deenergized and the spring Sic. will shift the valve 3! to a venting position. The result will be a centering of the pump yoke 5! by the spring pressed plunger or piston 82 and at the same time, the operating circuit is bypassed through lines 88, 9!, 92, a check valve H1, and a restriction H8. A sufficient resistance is thus affected in this bypassing to aid thebrake H5 in gradually bringing the load to a safe stop. The brake, of course, will be automatically engaged upon a shifting of valve 3% to venting position. In the case of power failure while hoisting, line 83 is closed by rod 65 since piston 53 is shifted to the left and hence the pump 2! will continue to raise the hoist carried on 'by the inertia by the high speed electric motor. Brake IE will, of course, be engaged as before but a fre wheeling device shown diagrammatically at H9, permits overrun while hoisting. The load is thus gradually decelerated by reason of gravity and this prevents the cable from whipping. As soon as the load comes to stop, the brake l5 will function to hold it and also the pressure will drop in line 55 thus permitting the plunger 83 to center the pump yoke. It will be seen that the pump yoke is always centered as a result of power failure and, as a. consequence, the electric motor is lightly loaded upon resumption of power.

t will further be seen that in the event of the rupture of any of the pressure lines, the brake IE will be engaged. In the event of the rupture of line 56, the booster pump pressure would be vented through line 59 and check valve 58 thus causing an engagement of brake l6. Rupture of line 55 would also vent the booster pump pressure through check valve I20, again causing the engagement of brake l 6.

Iclaim:

1. In a hoisting mechanism and control, an elevating mechanism, a hydraulic motor for driving said mechanism, and a pumping circuit for furnishing liquid under pressure to drive said motor including a variable displacement pump,

6 means onsaid pump shiftable to "hoist or lower positions for controlling the direction and volume of flow, and means'acting on said shiftable means to maintain it slightly towarda hoist position when the motor is not being operated.

2. In a hoisting mechanism and control, an elevating mechanism, a hydraulic motor for drivingsaid mechanism, and apumping circuit for furnishing liquid under pressure to drive said motor including a variable displacement pump, means on said pump shiftable' to hoist or lower positions for controlling the direction and volume of flow, control means acting on said shiftable means to maintain it slightly toward a hoist position when the motor-is not being operated, and valve means for bypassing the slight hoist output of said pump when said motor is not being operated.

3. In a hoisting mechanism. and control, an elevating mechanism, a hydraulic motor for driving said mechanism, and a pumping circuit for furnishing liquid under pressure to drive said motor including'a variable displacement pump, means on said pump shiftable to hoist or lo-wer.positions for controlling the direction and volume of flow, control means acting on said shiftable means to maintain it slightly toward a hoist position when the motor is not being operated. valve means for bypassing the slight hoist output of said pump when said motor is not being operated, and additional means responsive to a predetermined operating signal for removing the effect of said control means and cutting off said bypass.

4. In a hoisting mechanism and control, an elevating mechanism, a hydraulic reversible motor for driving said mechanism, and a pumping circuit for furnishing liquid under pressure to drive said motor including a variable displacement pump, means on said pump shift-able to hoist or lower positions for controlling the direction and volume of flow, control means acting on said. shiftable means to maintain it slightly toward a hoist position when the motor is not being operated comprising spring pressed plungers located in cylinders, valve means for bypassing the slight hoist output of said pump when said motor is not being operated, and additional means responsive to a, predetermined operating signal for cutting off said bypass and directing said pump output to said spring pressed plungers to remove the effect thereof on said shiftable means.

5. In a hoisting mechanism and control, an elevating mechanism, a hydraulic reversible motor for driving said mechanism, and a pumping circuit for furnishin liquid under pressure to drive said motor including a variable displacement pump, shiftable means on said pump movable to hoist or lower positions for controlling the direction and volume of flow, spring pressed plungers acting on said shiftable means to maintain the same slightly toward a hoist position when the motor is not being operated, an independent source of pilot pressure, a pressure operated means responsive to said pilot pressure and to a predetermined operating signal to control the position of said shiftable means during operation of said motor, and a valve means arranged to bypass the slight hoist output of said pump and to bypass the pilot pressure when the motor is not being operated, and shiftable to direct said pilot pressure to said pressure operated means and to direct said pump output. to

said plungers to remove the effect thereof on said shiftable means.

6. In a hoisting mechanism and control, an elevating mechanism, a hydraulic motor for driving said mechanism, a control cam driven by said motor, a pumping circuit for furnishing liquid under pressure to drive said motor including a variable displacement pump, means on said pump shiftable to hoist or lower positions for controlling the direction and volume of flow by its relative displacement from a neutral position, an operating lever, means operably connecting said lever and shiftable means whereby shifting of said lever will effect displacement of said shiftable means, and means connecting said lever and said cam whereby the limits of movement of said lever and said shiftable means are directly controlled by the position of said cam in its movement withthe motor, said cam being shaped to control acceleration and deceleration of said motor.

'7. In a hoisting mechanism and control, an elevating mechanism, a hydraulic motor for driving said mechanism, a variable delivery reversible pump for furnishing liquid under pressure to said motor, a movable member on said pump to control the output thereof, a source of pilot pressure, a follow-up valve for utilizing said pilot pressure toshift said movable member, a'brake means for said motor and a safety latch for said elevating mechanism, means connected with said brake means and said safety latch whereby said pilot pressure functions at the instance of an operator to release the same, and an independent mechanism operable upon failure of said pilot pressure to unlock said safety latch, release said brake,-'and render said follow-up valve inoperable.

8. In a hoisting mechanism and control, a hydraulic motor for driving a hoist mechanism, a reversible variable delivery pump for furnishing liquid under pressure to drive said motor, a movable member on said pump for controlling, by

7 its displacement, the direction and volume of flow from said pump to said motor, a source of power for driving said pump, and means responsive to a failure of said source of power for bypassing said pump during a lowering movement of said hoist. 9. In a hoisting mechanism and control, a hydraulic motor for driving a hoist mechanism, a reversible variable delivery pump for furnishing liquid under pressure to drive said motor, a movable member on said pump for controlling, by its displacement, the direction and volume of flow from said pump to said motor, a source of power for driving said-pump, means responsive to a failure of said source of power for bypassing said pump during a lowering movement of said hoist, and means for restricting said bypass flow to cause gradual deceleration of said hoist.

10. In a hoist, a driving mechanism comprising a motor. a variable displacement pump for furnishing liquid under pressure to said motor, movable means on said pump for controlling the direction and volume of flow, a follow-up mechanism for actuating said movable member, comprising a hydraulic motor, a valve for controlling pilot pressure thereto and means connecting the same to effect follow-up movement, manual means for controlling said valve, and means for locking certain elements of said follow-up mechanism to permit direct manual operation in case of failure of pilot pressure.

- 1 11. In a hoist, a driving mechanism comprising a motor, a variable displacement pump for furnishing liquid under pressure to said motor, movable means on said pump for controlling the direction and volume of flow, a follow-up mechanism for actuating said movable member comprising a hydraulic motor, a valve for controlling pilot pressure thereto, and means connecting the same to effect follow-up movement, manual means for controlling said valve, brake means for locking said motor except when released by pilot pressure, and means for locking certain elements of said follow-up mechanism and for releasing said brake means to permit direct manual operation in case of failure of pilot pressure.

12. In a hoist driving system, a, hydraulic motor, a-pump for furnishing pressurethereto, a closed circuit connecting said pump and said motor, a pilot pump for furnishing replacement liquid to said closed circuit, a liquid supply tank mounted'at a level above said circuit, and a valve connecting said tank with said circuit whereby said tank may furnish replacement liquid to said closed circuit in event of failure of said pilot pump.

13. In a hoisting system, a hoisting element, power means for actuating the same between a. lower station and an upper station, gate means at each of said stations to prevent access to the path of movement of said element while it is between said stations, a control system operatively connecting said gate means with said power means whereby said element may be shifted between said upper and lower stations only when said gate means are properly closed, and means for permitting limited movement of said element between twodefined and spaced levels at the upper station when said upper gate is open.

14. In a, hoisting system, a hoisting element, power means for actuating the same between a lower station and an upper station, gate means at each of said stations to prevent access to the path of movement of said element while it is between said stations, a control system operatively connecting said gate means with said power means whereby said element may be shifted only when said gate means are properly closed, means for permitting limited movement of said element between two levels at the top station when said top gate is open, and means for automatically decelerating said element at the lower end of its movement between levels at the upper station.

15. In a hoisting mechanism and control, a hydraulic driving motor, an elevating mechanism to be driven by said motor, a pumping circuit including a variable delivery pump for furnishing liquid under pressure to drive said motor, lines connecting the respective inlet and outlets of said motor and pump, a pressure release-brake operably connected to said mechanism for braking against downward movement only of said hoist, control means for bypassing said pumpmotor lines, control means for controlling pressure to said brake, electric power means for controlling said control means, and means responsive to power failure during hoisting to operate said control means to effect engagement of said brake to hold said hoist as it comes to rest, and responsive to power failure during lowering to open said bypass and effect engagement of said brake to bring said mechanism to rest.

16. In a hoisting mechanism and control, a hydraulic driving motor, an elevating mechanism to be driven by said motor, a pumping circuit including a variable delivery pump for furnishing liquid under pressure to drive said motor, lines connecting the respective inlets and outlets of said motor and pump, a pressure release-brake operably connected to said mechanism for braking against downward movement only of said hoist, control means for bypassing said pumpmotor lines, control means for controlling pressure to said brake, electric power means for controlling said control means, means responsive to power failure during hoisting to operate said control means to effect engagement of said brake to hold said hoist as it comes to rest, and responsive to power failure during lowering to open said bypass and eifect engagement of said brake to bring said mechanism to rest, and means forming a restriction in said bypass to aid in slowing down said motor during power failure in lowerm 17. In a hoisting mechanism and control, an elevating mechanism, a hydraulic motor for driving said mechanism, and a pumping circuit for furnishing liquid under pressure to drive said motor including a variable displacement pump, means on said pump shiftable to hoist" or lower positions for controlling the direction and volume of flow, means acting on said shiftable means to move the same to substantially neutral position in the absence of operating pres. sure in said pumping circuit but rendered inoperable by operating pressure, a pressure releasebrake operably connected to said mechanism for braking against downward movement only of said hoist, control means for bypassing said pumping circuit, control means for controlling pressure to said brake, electric power means for controlling said control means, and means responsive to power failure during hoisting to oper ate said control means to eifect engagement of said brake to hold said hoist as it comes to rest, and responsive to power failure during lowering to open said bypass and effect engagement of said brake to bring said mechanism to rest, said shiftable means being returned to substantially neutral position by the means acting thereon in each case of power failure.

18. In a hydraulic mechanism and control, an operating mechanism, a hydraulic motor element for driving said mechanism, a pumping circuit for furnishing liquid under pressure to drive said motor element including a pump element, means on one of said elements shiftable to positions for controlling the direction and volume of flow by its relative displacement from a neutral position, an operating lever, means operably connecting said lever and shiftable means whereby shifting of said lever will effect displacement of said shiftable means, and means operably connecting said lever and said operating mechanism to limit the movement of said lever and said shiftable means in a varying degree dependent on the position of the operating mechanism in its movement with the motor.

19. In a hydraulic mechanism and control, an operating mechanism, a hydraulic motor element for driving said mechanism, a; pumping circuit for furnishing liquid under pressure to drive said motor element including a pump element, means on one of said elements shiftable to positions for controlling the direction and volume of flow by its relative displacement from a neutral position, an operating lever, means operably connecting said lever and shiftable means whereby shifting of said lever will effect displacement of said shiftable means, a cam operated by said motor, and means connecting said lever and said cam comprising a cam follower mounted on said lever adapted to follow said cam and to limit the movement of said lever in varying degrees dependent on the movement of the motor from its starting position.

HARRY F. VICKERS. 

